A completely new drive concept
by Hans Diederichs
A completely new drive concept, which ensures quieter operation due to lower vibrations: Automotive supplier Hirschvogel draws this conclusion around one year after the start of production on a servo press in a compact design which was newly developed in collaboration with Schuler. In comparison with the previous installed presses at Hirschvogel, this faster working press is the first one with transverse instead of longitudinal shaft drive. Two counter-rotating eccentric gears in the head of the press balance the mass forces which improve quietness and precision.
The widely spaced pressure points also increase the available die area in the process flow direction. This creates space for another forming step which also allows the production of more complex forging parts. The transverse shaft drive also leads to a higher tilting rigidity of the press and lower deflection of the two crankshafts, and thus to a lower spring back of the entire machine.
With the four powerful servo motors of the new press, the speed at which the upper die approaches and moves away from the workpiece can be adapted precisely to the forming process. This allows full throttle during forming and slowing down when spraying and transporting the parts. In order to keep the temperature low on the active die, the contact time may be as short as possible without sacrificing the cooling and transport time.
The ServoDirect technology of the new press type allows individual adaptation to the respective forming process and can therefore guarantee optimal output. At the same time, the power management system saves energy at each stroke, as it is only supplied when it is needed. The table ejectors of the system also have an independent servo motor and are no longer mechanically coupled to the main drive, as in previous presses. This increases the flexibility for the parts transport with the highly dynamic two-bar transfer and additionally accelerates the production process.
According to Hirschvogel the system runs very satisfactorily. The 6,000-employees-company, which is one of the world's largest automotive suppliers in the area of forging and produced 376,000 tons of components last year, now has twelve machines from the press manufacturer in Göppingen.
Source and photo: Schuler AG